Two significant challenges in urban development are processing human and animal waste and providing adequate supplies of usable water. Treatment of waste, or “wastewater,” in urban environments, such as commercial and residential buildings, is a specific challenge. Wastewater is typically referred two in two classes—greywater and blackwater. Greywater, or “sullage,” is defined as wastewater generated from sinks, showers, baths, laundry, dishwashers and the like, which can be recycled on-site for uses such as toilet flushing, landscape irrigation and constructed wetlands. Blackwater refers to the discharge from toilets—i.e., water containing human waste. In commercial and residential buildings, grey-water and black-water are removed together, using a shared sewage system, to be treated at centralized waste treatment plants, before being returned to the environment at large. With anticipated increases in population and associated waste generation, waste management becomes one of the most critical aspects of sustainable development.
At the same time, there is a critical need to provide more and more potable water for urban growth. Many urban areas struggle to find enough water for the needs of their residents. Significant water conservation will be required to preserve freshwater to offset the limited supply and rising cost of potable water resources.
India provides just one example of the increasing need for wastewater management and potable water. India is the second largest country in the world, with a population of over 1.2 billion. It has one of the fastest growing economies in the world, recording over 896% growth over the last three years. Despite, or in some cases because of, this explosive growth, a large percentage of the Indian population still does not have access to safe water. On one hand, the pressures of development are changing the distribution of water in the country. On the other hand, access to adequate water has been cited as the primary factor responsible for limiting development. Only about half of the cities in India are supplied with piped water. For cities that have a population of between one and five million, their municipal authorities distribute water for only a few hours per day. The few hours that water is available, inadequate pipe pressure makes water delivery a struggle.
Meanwhile, the release of untreated wastewater in India has resulted in increased pollution and depletion of clean water resources. The most polluting sources of untreated wastewater are city sewage systems and industrial waste discharged into rivers. The facilities to treat wastewater are not adequate in any city in India. Presently, only about 10% of the waste water generated is treated, while the rest is discharged as-is into bodies of water.
Human and animal solid waste (feces) is composed of organic matter, which at least in theory could be incinerated or at least sterilized to eliminate bacterial activity and bad odor. A major problem associated with fresh feces, however, is their high water content, which inhibits incineration and unfortunately provides a good medium for bacterial growth and propagation. Furthermore, the high water content makes the feces sticky and dirty. Attempting to burn fresh feces by an external heat source, such as a gas burner, typically results in formation of an external layer of inorganic matter that insulates the wet interior and inhibits heat transfer and combustion thereto. Efficient heat transfer to the interior parts of the feces and water evaporation therefrom are essential components of fecal disposal by heat.
Innovators have previously attempted to circumvent this solid waste disposal challenge by mixing an oxidizing agent (e.g., potassium permanganate) with the waste to generate heat within the waste. This innovation is described for use on a small scale, in a pet waste collection device, in U.S. Pat. No. 8,096,597, which is hereby incorporated by reference in its entirety. No one, however, has developed a related or similar system or method for use in larger scale environments.
Therefore, it would be advantageous to have improved waste treatment systems and methods. Ideally, these systems and methods would provide for efficient treatment of greywater and/or blackwater treatment and would also conserve water. It would also be ideal if such systems could be installed on-site in commercial or residential buildings or in a portable configuration on a truck or other vehicle. At least some of these objectives will be met by the embodiments described below.